This invention relates generally to manufacture of semiconductor devices and more particularly to interface units used to interface a test system to a device under test.
In the manufacture of semiconductor devices, the semiconductor devices are usually tested at least once during the manufacturing operation. The results of the testes are used to control further processing in the semiconductor manufacturing operation. The testing might be used to separate properly operating devices from devices that fail to operate properly. However, testing can also be used to feed back data to other stages in the manufacturing operation to make adjustments that increase the yield of properly operating devices. In other instances, the test results are used to sort devices into performance categories. For example, a device might operate at data rates of 200 MHz, but not operate at data rates of 400 MHz. Following testing, the device might be classified as a 200 MHz device and sold at a lower price than a 400 MHz device.
A testing stage might also be used to make physical changes to the device under test. Many semiconductor devices with memories contain redundant elements. If defective memory cells are discovered during testing, the semiconductor device might be sent to a repair station, such as a laser repair station, where connections on the device are rearranged to disconnect the faulty cells and connect redundant elements in their places.
Testing is generally performed by Automatic Test Equipment (ATE). A tester contains the circuitry that generates and measures the electrical signals needed to determine if the device is properly functioning. A separate material handling device moves the semiconductor devices to the tester. A material handling device is often called a xe2x80x9chandlerxe2x80x9d when the semiconductor devices are being tested after they have been packaged. A material handling device might alternatively be called a xe2x80x9cproberxe2x80x9d, which is used when the semiconductor devices are tested while still on a wafer. In general, the tester and the material handling device are assembled into a work cell, with the specific characteristics of the tester and material handling device being selected based on the type of devices that are to be tested.
To allow the tester to make connections to many different types of devices, an interface unit is used. Often, the interface unit has many compliant probes or contacts. The material handling device presses the devices to be tested against these probes or contacts so that electrical signals can move between the device under test and the tester. For testing packaged parts, the interface unit is often called a xe2x80x9cdevice interface boardxe2x80x9d or xe2x80x9cDIBxe2x80x9d.
The present invention is, in its preferred embodiment, used in connection with a material handling unit for moving packaged parts to a DIB. Therefore, the description of the preferred embodiment that follows uses a packaged part handler with a DIB as an example.
The layout of the contacts on the interface unit must line-up with the test points on the devices being tested, a different interface unit is usually required for each type of semiconductor device being tested. Because a semiconductor manufacturer will generally want to use a work cell to test different kinds of semiconductor devices, the interface unit is made a separate part from the material handling unit or the tester. In this way, the work cell can be reconfigured to test whatever kinds of parts the semiconductor fab is producing.
For example, a DIB is usually attached to a material handling unit with screws that can be removed to remove the DIB. Once the DIB is attached to the material handling unit, the tester, or at least a test head portion of the tester, is then pressed against the material handling unit. Spring pins or other form of compliant contacts make electrical connection between the DIB and the tester.
In manufacturing semiconductors, it is desirable that the equipment in the fabrication facility be in service as much as possible. Taking equipment out of service, even to make routine adjustments to the equipment, can reduce the cost effectiveness of the entire manufacturing operation. For that reason, it is desirable that the process of changing a DIB in a test work cell be done as quickly as possible. Finding special tools to attach or detach a DIB is therefore a disadvantage.
In some prior art ATE, clamps, cams or the like are used to hold the DIB to the handler. In this way, a DIB can be removed and a new one can be installed without the time needed to remove screws. However, significant time is still required to change a DIB.
The DIB is located between the tester and the handler. To access the DIB, the tester must be moved. To allow for access to the DIB, most testers are mounted on devices called a xe2x80x9cmanipulator.xe2x80x9d The manipulator allows the tester to be aligned with the handler. Considerable flexibility in positioning the tester is possible with most manipulators. To provide access to the DIB, the manipulator can swing the test head out the way.
But, once a new DIB has been installed, the tester must be re-aligned with the handling device and then reconnected to it. The process of aligning the tester and handler and connecting them together is sometimes called xe2x80x9cdocking.xe2x80x9d Un-docking and re-docking the tester and handler during a DIB change can still take a significant amount of time, even when a clamp, cam or similar device holds the DIB to the handler instead of screws.
In addition, a traditional DIB changing operation exposes sensitive and easily damages parts of the tester and the handler. For example, spring pins making electrical connection between the tester and the DIB might be damaged.
Further, special training is sometimes needed to ensure that the operator properly installs the DIB. If not properly installed, damage to the tester, handler or DIB might occur and the semiconductor manufacturing operation might be disrupted.
With the foregoing background in mind, it is an object of the invention to provide an improved way to change an interface unit in a semiconductor manufacturing facility.
The foregoing and other objects are achieved in which an ATE work cell is equipped with a changer for an interface unit between a tester and a material handling unit. The changer allows the interface unit to be changed with only a small amount of separation between the material handling unit and the tester.
In one aspect, the invention allows an interface unit, such as a DIB, to be easily installed. The changer guides the interface unit into course alignment through translation in a direction parallel to the mating interface between the material handling unit and the tester. Then, the interface unit moves in a direction perpendicular to the mating interface, with fine alignment in a direction within the plane being provided by alignment features that operate as the interface unit moves perpendicular to the mating interface.
In another aspect, the invention allows an interface unit to be easily removed. The interface unit moves perpendicular to the mating interface to disengage from alignment features. Then, the interface unit moves perpendicular to the mating interface to a position where it can be easily removed by a human operator.